NU FS100 Lecture Notes - Lecture 5: Ionizing Radiation, Irradiation, Frozen Food

• School: University of Alberta
• Department: Nutrition and Food Sciences
• Course: NU FS100
• Professor: Wendy Wismer

Document Summary

Drying and freezing processing both remove water from food. Processes are very similar, make water unavailable for microbes growth. The goal of heat sterilized (cid:272)a(cid:374)(cid:374)i(cid:374)g is (cid:862)(cid:272)o(cid:373)(cid:373)er(cid:272)ial sterility(cid:863) Destruction of all pathogens, heat resistant microbes that could grow under normal storage conditions. Spores of bacteria could survive (not concerned about them because they wont grow in the conditions that food is normally stored in) Need to consider: microbial heat resistance, heat transfer ability of the food (faster in a liquid than a solid, type/size of container used. Conduction: heat transferred from molecule to molecule via collisions (heat moves from outside to inside) Convection: heat transferred through a liquid which circulates. Heat (cid:373)ust get to the (cid:862)(cid:272)old spot(cid:863) i(cid:374) the (cid:272)a(cid:374: very last spot in the can to receive heat. Some foods have heat transfer through both conduction and convection. Used to describe heat resistance of microbes. What combination of temperature and time is required to destroy microbes.